My Network Places not responding

Hello.
After going to My Network Places and then clicking on the link in the left pane "View Workgroup computers" I get an error message after a few seconds stating that the application is not responding and needs to close. Until recently other people were still able to access my computer from their's and so I didn't worry about it, but after a computer in my workgroup was recently upgraded, that PC can no longer see mine and we cannot transfer files over the network. However I am also using Hamachi as a VPN and CAN access the files of the computers on that netwrok. The VPN computers and my computer and the other computer on the LAN(which cannot see mine) are all in the same workgroup. When I use the "Net View" command, I can see all computers on my LAN and the VPN. but cannot ping the ones on my LAN.

I am running Windows XP SP2 and have a Compaq Presario S5000CL that someone gave me free (only until I can get some $$ to buy a new one). I have 512 MB of RAM and a 2.13 GHZ AMD Athalon 2600+ processer.I am using the onboard ethernet on an MSI MS-6390 3.0 motherboard. I know this hard drive has some problems but none that would cause this that I know of. It is a SAMSUNG SV0802N (80.06 GB). It accessed the pagefile to much because of not having enough RAM and I think it might have gotten scratched or somthing.

Please help.
P.S. I am still sort of a PC noob, (I am about to take the A+ certification exam). So please use semi-basic terms in you replys.

Also my next question is:

Are your computers connected on a network with a domain or are all computers connected over a workgroup?

Can you ping any machines by name?

Can you ping machines by IP address?

If you open a run dialog box and type "\\ipaddressofworkstation" and then hit enter do you get a list of files being shared by your PC or another PC on the network? If that works try the same command only input a computers name instead of IP address.

P.S. Sorry about the long time without a response: I only remered that I posted this when I found it on Google lol...